:root {
    /* Customize Material palette subtly if desired */

    /* Enhanced styling for accordion toggle buttons */
    .toc-accordion-toggle {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        min-width: 1.5rem;
        min-height: 1.5rem;
        margin-right: 0.25rem;
        padding: 0.125rem;
        border: none;
        background: transparent;
        cursor: pointer;
        font-weight: bold;
        font-size: 1rem;
        color: var(--md-default-fg-color);
        transition: color 0.2s ease, transform 0.2s ease;
        border-radius: 0.25rem;
    }

    /* Hover state - provide visual feedback */
    .toc-accordion-toggle:hover {
        color: var(--md-primary-fg-color);
        background-color: rgba(0, 0, 0, 0.05);
        transform: scale(1.15);
    }

    /* Active state - when aria-expanded is true */
    .toc-accordion-toggle[aria-expanded="true"] {
        color: var(--md-primary-fg-color);
    }

    /* Focus state for accessibility */
    .toc-accordion-toggle:focus {
        outline: 2px solid var(--md-accent-fg-color);
        outline-offset: 2px;
    }

    /* Optional: hint collapsed items with slight opacity change */
    .toc-collapsed > .md-nav__link {
        opacity: 0.85;
    }
}